Bird guard for electrical protective devices



C. A. FOX

Jan. 21, 1947.

BIRD GUARD FOR ELECTRICAL PROTECTIVE DEVICES Filed Feb. 7, 1945 R m N E v m CHARLES ADIN F'ox AT TQRNEY.

Patented Jan. 21, 1947 BIRD GUARD FOR ELECTRICAL PROTEC- TIVE DEVICES Charles Adin Fox, Oakland Village, M0,, assignor to James R. Kearney Corporation, St. Louis, Mo., a corporation of Missouri Application February 7, 1945, Serial No. 576,603

7 Claims. 1

This invention relates generally to electrical protective devices which are adapted for use in protecting equipment associated with electrical circuits in wh ch the protective devices are interposed, from the damaging effects of overloads, short-circuits, and surges. the predominant object of the invention being to provide an electrical protective device of the type mentioned that incudes guard means which i so arranged as to prevent a bird from short-circuiting the device by perching on a live part of the device and pecking at another grounded part of the device so as to thereby establish a short-circuit between said parts through the body of the bird.

Fig. 1 is a front elevation of a combination cutout and lightning arrester which is provided with a bird guard in accordance with this invention.

Fig. 2 is a horizontal section taken on line 2-2 of Fig. 1.

Fig. 3 is a fragmentary side elevation of the lower portion of the protective device illustrated in Fig. 1.

In the drawing, wherein is shown for purposes of illustration, merely, one embodiment of the invention, A designates generally an electrical protective device. The particular protective device illustrated in the drawing comprises an insulator I, of the petticoat type, at the upper end of which an upper terminal 2 is suitably fixed. The upper terminal 2 has secured thereto an outstanding contact arm 3, and said upper terminal 2 'mcludes a loop portion 4 to which the incoming conductor (not shown) of the protective device may be attached by a suitable connector 5.

At its lower end the insulator I has suitably secured thereto a lower terminal 6 on which a lower contact arm 1 is mounted, and to which the outgoing conductor (not shown) of the protective device A may be attached by a suitable connector 6. The lower contact arm I is formed from a length of wire, or rod material, which is inherently resilient, said lower contact arm being so shaped and arranged as to have a loop portion 8 which is secured to the lower terminal 6 by a bolt and washer assembly 9, a pair of spaced coils l into the centers of which are extended contact arm portions which lead from said loop portion 8, portions l l which lead from the outer portions of the coils and merge into convergent contact arm portion-s l2, closely related, parallel portions l3 which extend from said convergent portions l2, and rearwardly bent portions I4 at the outer ends of the portions 13 which provide fuse link gripping portions. The outer end portion of the all) lower contact arm I has applied thereto a cap [5, and the closely related, parallel portion I3 of said lower contact arm are embraced by bands IS.

The upper contact arm 3 is provided at its outer end with fuse link gripping portions similar to the fuse link gripping portions provided by the rearwardly bent portions M of the lower contact arm I, and flexible conductors I1 and [8 of a fuse link F are gripped by said fuse link gripping portions of said upper and lower contact arms when the protective device is in a fused condition, as is shown in Fig. l. The fuse link F includes a fusible section (not shown) which is embraced by a tube !9 formed of suitable insulating material, and when the conductors l1 and 18 of the intact fuse link are engaged by the gripping portions of the upper and lower contact arms 3 and 1, the outer end portion of the lower contact arm I is held in an elevated position by the fuse link. Because of the maintenance of the outer end portion of the lower contact arm I in an elevated position by the intact fuse link the spirally coiled portions IU of said lower contact arm are tensioned so that force is stored up in said coiled portions which tends to swing the outer portion of the lower contact arm I downwardly, and when the fusible portion of the fuse link is ruptured by a short-circuit or overload in the circuit the outer portion of said lower contact arm swings downwardly to quickly separate the portions of the ruptured fuse link.

The protective device A illustrated in the drawings includes, also, means for arresting surges caused by lightning and other causes. .The surge arresting means comprises a member 20 which is suitably supported by the upper terminal 2 and extends outwardly therefrom. Associated with the member 26 is an arm 2| which is so related to said member 20 that a gap 22 is provided between a portion of said member 2i! and a portion of said arm, as is shown in Fig. 1. The arm 2! is fixed to a support 23 which is secured to the insulator l by a U-bolt 24, said support 23 having secured to it, also, an upper contact arm 25.

The insulator I of the protective device A is provided with a bracket 26 which serves as means for mounting the device on a cross arm, or other support. The bracket 23 includes a portion 21 which embraces a portion of the insulator i, and fixed to a supporting element 28, which is associated with said embracing portion of said bracket, is a lower contact arm 29. The lower contact arm 29 is constructed and arranged in accordance with the lower contact arm 5, previously described herein, said lower contact arm 29 being formed from a length of resilient wire, or rod material, and being provided with spaced, spirally coiled portions 30, one of which is shown in Fig. 1, and having rearwardly bent portions 3! at its outer end, one of which is shown in Fig. 1, which provide said lower contact arm 29 with gripping portions. IChe upper contact arm is provided with reawardly bent portions 32 at its outer end, one of which is shown in Fig. 1, that produce gripping portions, and the gripping portions of said upper contact arm 25 and said lower contact arm 29 engage flexible conductors 33 and 341 of a surge tube structure S which is of suitable construction and arrangement to perform its intended function.

The bracket 26 is grounded, as is indicated diagrammatically in Fig. 1, and when, in the use of the protective device A, a surge on the line seeks a path to ground it will form an arc across the air gap 22 (which normally keeps the line potential oil of the surge tube structure S) and across a gap (not shown) within the surge tube structure S, and will pass to ground by way of the lower contact arm 29 and the bracket 26. A tollow-up power are will be established across the gap within the surge tube structure and this follow-up power are will be extinguished within the surge tube structure. If, however, the surge tube structure fails .toproperly extinguish the power are, the continuance of the arc will destroy the surge tube structurelby burning same so that its opposite endportions are separated, and when this occurs the outer end portion of the lower contact arm 29 will swing downwardly in response to force imparted by the tensioned spirally coiled portions 30 of said lower contact arm 29 to quickly jerk the surge tube structure S apart, and thereby freethe protective device from ground by creating .an air gap which will prevent re-establishment of an.arc.,

It has been found in the use of an electrical protective device such, for instance, as that shown in the drawing hereof anddescribed above, that birds frequently perch on the upper portions of the energized, spirally coiled portions ll! of the lower cont ct arm i, and peek at adjacent grounded portions of the surge arresting means of the device. When this occurs a short-circuit is established through the body of the bird from the lower contact arm 7 to ground and the fuse link F is ruptured, thereby interrupting service on the circuit. Theprime purpose of this invention is to provide a protective device with means which prevents a bird from so short-circuiting the protective device, and. this means will now be described.

The preventive means referred to above comprises a guard in the form of a sheet of electrical insulating material which possesses the required resiliency, one material which has been found to be entirely suitable for the purpose being Bakelite. The sheet 35 of insulating material is of partial circular shape, as is shown in Fig. 2,

and said sheet of material is provided with a cutout portion 36 which likewise is of partial circular shape and is eccentrically arranged with respect to the partially circular sheet 35. The wall of the cutout portion 36 and the outer marginal edge ofthepartially circular sheet of material 35 are joined by a pair of flared edge portions 31 of the sheet of material which provide atapered opening portion that serves as an entrance to the partially circular cutoutportion 36.

The sheet of, material 35 is applied to a portion of the insulator i which defines the recess between the lowermost petticoat of the insulator and. the next higher petticoat, and when so applied the sheet of material is disposed immediately above the coiled portions IQ of the lower contact arm '5, as is shown in Figs. 1 and 3. To apply the sheet of material to the insulator, said sheet of material is arranged in a, horizontal-position at the recess of the insulator where it is to be applied, with the recessed insulator portion extending partially into the cutout portion of the sheet of material, as is shown by dotted lines in Fig. 2. The sheet of material is then forced onto the recessed insulator portion sothat the partially circular edge of the cutout portion 38 contacts closely with the circumferential face of the recessed insulator portion.

It is important to note that the diameter of the cutout portion 35 of the sheet of material 35 is slightly less than the diameter of the insulator portion at the base of the recess in which the sheet of material is applied to the insulator, and because of this fact, and due to'the resilient nature of the sheet of material, portion of saidsheet of material will yield as the sheet of material is forced onto the insulator. Also, when the sheet of material has been completely applied to the insulator the edge of the cutout portion 36 of the sheet of material 35, which describes an arc of greater than of a circle, will closely grip a correspondin portion of the circumferential face of the insulator portion to which said sheet of material is applied, and hence the sheet or material 35 will be very securely attached to the insulator i of the protective device A without the need for fastening devices of any sort for accomplishing such attachment.

When the guard has been applied to thcinsulato-r as described, it overlies the coiled portions iii of the lower contact arm i so that a bird-may not perch thereon, as has been possible in. the past when no protectiveguard was employed. IAISO, if a bird should perch on the guard and, peck at a grounded part of the protective device no shortcircuit would be produced because of the electrical insulating nature of the guard.

If desired, the sheet of material 35 which provides the guard may be provided with a downturned lip 38, which, when the guard is in place in association with the insulator I, is disposed between the spaced coils it of the protective device A. Thelip 33 is of only slightly less width than the space between the spaced coils i6, and hence the disposition of said lip between said spaced coils willprevent any rotation of the guard with respect to the insulator if there should be any looseness between the edge of the cutout portion 35 of the guard and the circumferential face of the insulator.

I claim: 7

1. In combinationwith an electricalprotective device comprising an insulator of the petticoat type that supports an energized device part and a grounded device part, a guard comprising a sheet of electrical insulating material which is supported by said insulator so that it overlies said energized part of said protective device, said sheet of electrical insulating material being provided with a cutout portion and an entrance opening which leads from the outer edge of said sheet of insulating material into said cutout portion, said cutout portion of said sheet of insulating material having an edge which describes an arc of morethan 188 of a circle that isseated between an adjacent pair of ribs ofsaid insulator and clo filx grips a face portion of said insulator:lo-

5 cated between and at the bases of said adjacent pair of insulator ribs to efiect attachment of said guard to said insulator.

2. In combination with an electrical protective device comprising an insulator that supports an energized device part and a grounded device part, a guard comprising a sheet of electrical insulating material which is supported by said insulator so that it overlies said energized part of said protective device, said sheet of electrical insulating material being provided with a cutout portion and an entrance opening which leads from the outer edge of said sheet of insulating material into said cutout portion, said cutout portion of said sheet of insulating material being arranged eccentrical- 1y with respect to said sheet of insulating material and said cutout portion having an edge which describes an arm of more than 180 of a circle that closely grips a face portion of said insulator to effect attachment of said guard to said insulator.

3. In combination with an electrical protective device comprising an insulator that supports an energized device part and a grounded device part, a guard comprising a sheet of resilient electrical insulating material which is supported by said insulator so that it overlies said energized part of said protective device, said sheet of electrical insulating material being provided with a cutout portion which is arranged eccentrically with respect to said sheet of insulating material, and an entrance opening which leads from the outer edge of said sheet of insulating material into said cutout portion, said cutout portion being adapted to receive therein a portion of said insulator and said cutout portion being of slightly less diameter than the diameter of the insulator portion received therein, whereby the resilient nature of said sheet of insulatin material will cause the edge of said cutout portion to closely grip a face portion of the insulator portion received within said cutout portion to effect attachment of said guard to said insulator.

4. In combination with an electrical protective device comprising an insulator that supports an energized device part and a grounded device part, a guard comprising a sheet of resilient electrical insulating material which is supported by said insulator so that it overlies said energized part of said protective device, said sheet of electrical insulating material being provided with a cutout portion which is arranged eccentrically with respect to said sheet of insulating material and an entrance opening which leads from the outer edge of said sheet of insulating material into said cutout portion, said cutout portion being adapted toreceive therein a portion of said insulator and said cutout portion being of slightly less diameter than the diameter of the insulator portion received therein and having an edge which describes an arc of more than 180 of a circle, whereby the resilient nature of said sheet of insulating material and the shape of said cutout portion will cause the edge of said cutout portion to closely grip .a face portion of the insulator portion received within said cutout portion to efiect attachment of said guard to said insulator.

5. In combination with an electrical protective device comprising an insulator that supports an energized device part and a grounded device part, a guard comprising a sheet of electrical insulating material which is supported by said insulator so that it overlies said energized part of said protective device, said sheet of electrical insulating material being provided with a cutout portion having an edge which closely grips a face portion of said insulator to effect attachment of said guard to said insulator, and an extension on said guard that is disposed adjacent to said energized part and which prevents rotation of said sheet of electrical insulating material with respect to said insulator by abutting against a portion of said energized part.

6. In combination with an electrical protective device comprising an insulator that supports an energized device part and a grounded device part, a guard comprising a sheet of electrical insulating material which is supported by said insulator so that it overlies said energized part of said protective device, said sheet of electrical insulating material being provided with a cutout portion and an entrance opening which leads from the outer edge of said sheet of insulating material into said cutout portion, said cutout portion of said sheet of insulating material having an edge which describes an arc of more than 180 of a circle that closely grips a face portion of said insulator to effect attachment of said guard to said insulator, and an extension on said guard that is disposed adjacent to said energized part and which prevents rotation of said sheet of electrical insulating material with respect to said insulator by abutting against a portion of said energized part.

7. In combination with an electrical protective device comprising an insulator that supports an energized device part and a grounded device part, a guard comprising a sheet of electrical insulating material which is supported by said insulator so that it overlies said energized part of said protective device, said sheet of insulating materia1 being provided wtih a cutout portion having an edge which closely grips a face portion of said insulator to eifect attachment of said guard to said insulator, and an extension on said guard which is adapted to abut against a part of said protective device so as to prevent rotation of said guard with respect to said insulator.

CHARLES ADIN FOX. 

